The RA-8 Argentine reactor, whose special mission was to test the core of the future reactor called Argentine Modular Element Facility (CAREM, in Spanish), was designed and built by INVAP for the Argentine National Commission of Atomic Energy (CNEA, in Spanish) located in Pilcaniyeu, Province of Río Negro, Argentina. It was in operation from 1997 to 2001. These kind of reactors usually have low power and short lifetime since they go out of service once their mission is complete. Although they are formally similar to open pool research reactors, their purpose is different: to test the quality of fuel elements and the core design in a physical real scale model.
The RA-8 is an open pool non-power reactor. It generates only 10 W of thermal power, with a maximum of 100 W in full operation. With such low thermal conductivity, there is no need for a complex cooling circuit. Weak pool water convection is enough to cool the core. Fuel elements used by the RA-8 during its short lifetime will activate the future CAREM nuclear plant: Zircaloy pipes with low enriched uranium dioxide in ceramic pellets.
This material contains a U235 fissile isotope concentration that may be from 1.8% to 3.4% of the total uranium inventory according to the core's position.
CAREM control elements –made up of silver, indium and cadmium plates intended to absorb neutron excess– were also tested in the RA-8.